Engine starter gearing



18, 1959 G. s. SPENCER 2,900,526

ENGINE STARTER GEARING Filed Oct. 25, 1957 INVENTOR.

. WMYW A TORNEI United States Patent 2,900,526 I ENGINE STARTER GEARINGGlenn S. Spencer, Horseheads, N.Y., assignor to Bendix AviationCorporation, Elmira Heights, N.Y., a corporation of Delaware ApplicationOctober 23, 1957, Serial No. 691,985

4 Claims. (Cl. 290-38) The present invention relates to engine startergearing and more particularly to that type in which the initialengagement of the gearing is brought about by axial movement of thestarting motor shaft.

In engine starter gearing of this type such as shown for instance in thepatent to Buxton 2,396,986 issued March 19, 1946, it has been founddesirable to incorporate some form of latching means to hold the motorarmature in centered position as long as the starting switch is closed,irrespective of variations in load caused by initial explosions in theengine. This makes it possible to use a decentering return spring ofsuflicient stiffness to insure against undesired engagement of thepinion due to accelerational forces of the vehicle on which the deviceis mounted.

It is an object of the present invention to provide starter gearing ofthe above type incorporating a novel form of positive latching means forholding the armature in centered position during cranking.

It is another object to provide such a device in which the latchingmeans is actuated directly by the solenoid which controls the startingswitch.

It is another object to provide such a device in which the latchingmeans is released and moved out of operative position when said solenoidis deenergized.

Further objects and advantages will be apparent from the followingdescription taken in connection with the accompanying drawing in whichthe figure illustrates a preferred embodiment of the invention in sideelevation, partly broken away and in section, the electrical elementsbeing shown partly in diagrammatic form.

In the drawing there is illustrated a starting motor 1 which is adaptedto be energized by a battery 2 under the control of a magnetic relayswitch indicated generally by the numeral 3. The motor 1 comprises astationary field 4 and a rotary armature 5 mounted on a shaft 6 which isslidably and rotatably mounted in bearing-s 7 and 8 in the ends of themotor frame. The armature shaft 6 carries a pinion 9 slida'blyjournalled thereon for movement into and out of mesh with a gear 11 ofthe engine to be started. The pinion is connected to the armature shaftby an overrunning driving and traversing connection which forms no partof the present invention but which is shown and described in the patentto Buxton above sited.

The armature 5 of the motor is provided with a commutator 12 cooperatingwith brushes 13 in the usual manner, and a thrust spring 14 is locatedbetween the commutator 12 and the end bearing 7 of the motor to therebynormally maintain the armature 5 displaced to the right from centeredposition with respect to the field 4.

The relay switch 3 is mounted on a threaded extension of the motorbearing 7 as indicated at 15 and is provided with a plunger 10 which islocated in alignment with the armature shaft 6 and has a latch member16, swiveled thereon as indicated at 17. Latch 16 has a plurality ofelastic arms with hook-shaped terminals 2,900,526 Patented Aug. 18, 195918 normally engaging the tapered end 19 of the bearing extension '15whereby the hooks are spread apart wider than the diameter of thearmature shaft 6. A spring 21 in the relay 3 normally holds the plunger10 in the extended position as illustrated.

The relay 3 is provided with a solenoid coil 23 energized from thebattery 2 by means of a manual switch 24 and when so energized it movesa contact 25 on the plunger 10 to bridge the stationary contacts 26, 27and thereby complete the starting motor circuit.

The armature shaft 6 is provided near its end with a tapered latchgroove 28 in position to receive the hooks 18 of latch 16 when the relayswitch is closed, and when the armature 5 is in centered relation withrespect to the field 4 of the starting motor.

In operation, starting with the parts in idle position as illustrated,closure of the manual switch 24 energizes the coil 23 of the relay 3,which attracts the plunger 10 causing closure of the relay switch 25,26, 27. This movement of the plunger withdraws the hooks 18 of the latch16 from the tapered extension 19 of the motor bearing and permits themto approach each other to the positions shown in dotted lines in thedrawing. The consequent energization of the starting motor causes thearmature 5 to center itself with respect to the field 4, thereby movingthe armature shaft 6 to the left until the hooks 18 enter the groove 28in the armature shaft and thereby latch the armature in its centeredposition.

The longitudinal movement of the armature shaft 6 brings the pinion 9into initial engagement with the engine gear 11, and the rotation of themotor causes the further translation of the pinion into full mesh Withthe engine gear and ensuing cranking of the engine in the usual manner.During the cranking operation, the armature is not permitted to driftaway from its centered position even though the flux through the motormay temporarily diminish responsive to initial explosions of the engine.The pinion 9 is thus maintained in engagement with the engine gear 11irrespective of temporary overrunning of the pinion due to false startsof the engine.

When the engine is reliably self-operative, the operator opens theswitch 24, thus releasing the plunger 10 which is returned to its idleposition by the spring 21, the hooks 18 of the latch being againexpanded out of contact with the armature shaft by engagement with thetapered end 19 of the motor bearing. The spring 14 is then free toreturn the armature to its idle decentered position as illustrated.

Although but one form of the invention has been shown and described indetail it will be understood that changes may be made in the design andarrangement of the parts without departing from the spirit of theinvention.

I claim:

1. In an electrical starting system for internal combustion engines amotor having a field and an armature which is shiftable axially into andout of centered position with respect to the field, an armature shaft, apinion slidably mounted for movement thereon and therewith into and outof mesh with a gear of the engine to be started, an overrunning drivingconnection from said shaft to the pinion, means for energizing thestarting motor including an eleetro-magnetic starting switch having aplunger in alinement with the armature shaft and spaced axiallytherefrom, said shaft having a circumferential groove adjacent its end,and a latch member mounted on said plunger and movable thereby onclosure of the starting switch into position to engage said groove whenthe motor armature is in central position.

2. An engine starting system as set forth in claim 1 including furthermeans for disengaging the latch from the motor shaft responsive toopening the starting switch.

switch is sufiiciently'powerfill to hold the armature in centeredposition 'by'means'ofthe plunger and latch connection, irrespective ofvariations in the energization of the starting'motor.

4. An engine starting system 'as set forth in claim 2 in'which the latchmember is elastically expandable, "and the means for disengaging itfrom-th'eshaft comprises a tapered projection on the motor frame whichwedges the latch open when the switch plunger moves to its openposition.

References Cited in the file of this patent UNITED STATES PATENTS1,308,158 Bijur July 1, 1919 2,151,492 Weiss Mar. 21, 1939 2,394,531Buxton Feb. 12, 1946 2,396,986 Buxton Mar. '19, 1946

